My homemade PC-based "Coal Trol" and stoker control theory

WissaMan wrote:Cool, I'm glad I'm not the only person that's had these kinds of ambitions. My wife says it "must be a guy thing" to want to "control" stuff I realize I could have a coaltrol and have more free time, but I enjoy the challenge of a project like this, which is well suited for winter time since I can't work on any outdoor projects...

I actually have this system working, so I'm past the theory stage. I am currently using an older HP PC (<1ghz) as a dedicated controller running a fresh, clean install of XP. XP is actually pretty stable as long as you don't have tons of stuff installed on it (though if I had the knowledge, I'd rather do it with a Linux...but alas) As for some of your other concerns...it will not have internet connectivity so auto updates/reboots are no problem. Currently my program is set to load at startup so if there is a power failure, the PC will reboot automatically and with only the OS loading, it boots to desktop in under 30 seconds. All important variables are written to disk every time the program cycles through the control loop, so upon reboot the program can "pick up where it left off". Though all that asided, a UPS is in my long-term plans.

The interface I use is a Phidget (http://www.phidgets.com) which has digital and analog inputs and digital outputs and connects to the PC via USB. That is really the key piece to my setup and w/o that I wouldn't be able to do this. The second key piece is that I was able to use the Phidget C+ API with Clarion (Clarion is a somewhat obscure, but very powerful language I program in and is the only language I have any skill in these days). I do think that Arduino piece looks nice and if I wasn't already commited with this particular setup, I probably would consider it. Another setup I did consider was using MS Robotics Studio, but after my initial tests with Clarion were successful, I abandoned that idea quickly since it would've meant learning a whole new language.

Regarding the blower control, I am using the Phidget interface to turn the fans and pusher motor on and off using solid-state relays I pulled from old copiers (which are a treasure trove of components ) I don't plan on trying to modulate the speed of the fans, only turn them on/off for variable periods of time. I think the Phidget interface can turn on/off it's outputs pretty quickly so theoretically I could control the speed by turning them off/on rapidly but I'm not sure that would be good for the motor. Old copiers also have a multitude of 24v DC fans which could be modulated by voltage but unfortunately, Phidgets does not make an interface with analog outputs so I currently have no way of controlling devices other than with on/off.

eelhc, I do plan on using a thermal probe to regulate the stove temperature, however my goal is to regulate it in relation to the outside temperature (as well as the inside) and run the distribution blower constantly. I feel like if the stove is producing heat and I'm not utilizing it, then it is being wasted, so I'd rather lower the stove temperature when less heat is needed and keep the blower constant than vice versa. Although I may change that idea once I install the DHW coil.

Cheers,
Wissaman

DVC500 at last wrote:

Bratkinson wrote: COBOL, FORTRAN and PL/I. I lost count of how many assembler languages and databases I’ve learned and forgotten… (4 different 14xx IBM models I used way back in the mid-late 60’s each used a variation of Autocoder, and then came the 70xx boxes….). Bottom line, there’s a learning curve just to get everything ‘talking’.

Well your talking my language now I still remember coding the cc tapes for the 1403's when I was in the AirForce. Installed a BASIC compiler on the 360 system. Mostly wrote in Fortran IV, later in SAS, lator wrote the IODFs for the mainframes. HCD was a nice improvement over the old card-image setup. That was a LONGGGG way from today's Z/OS systems (which I love!)
Yep, I'm still happy with the controller in my DVC-500. Thats why I bought it. I have no interest in Over-designing something that probably wouldn't do a better job anyway.

europachris wrote:However, it does not have thermocouple or RTD inputs, and the outboard converter is pretty expensive. So, I plan to use an Automation Direct PID temp controller and use it to signal the PLC for heat and also use the alarm outputs for under/overtemp, etc. It should make the programming simple, too.

It would probably be just as easy to do it with a handful of relay sockets and relays......but not as fun.

Chris

Highlander wrote:I do not see too many PC based process or machine controls in my work, the general industry trend is towards PLC's or embeded microprocessor designs for long term reliability.

BlackRockBurner wrote:The MicroLogix system is up and running. I'm working on setting the proper idle feed times.
The green light in the bottom left tells when it's calling for heat, the white light is when it's idling.
The red pushbutton will blink if the stove ever hits the high temp limit until it's pushed to reset the alarm, so I know
what the stove is doing when I'm away. The switch turns the system on and off, and the two sets
of BCD thumb switch's are for the feed motor on and off time during idle. I mounted the system in the
laundry room about 10ft from the stove and ran two cables over to it. One for the 24v inputs and
the other for the 110v motor feeds. Each cable has a few spares in it in case I want to expand my
inputs or outputs in the future. Here's a Pic..

Mark